I was at Clarence's the other weekend, and had been wanting to measure a G90 with the Marquee C-element mod. I thought others might be interested in the comparison.

G90 (stock)
x =.330 y =.587

G90 w/Marquee C-element
x =.311 y =.603

SMPTE "C" green primary
x =.310 y =.595

SMPTE HD green primary
x =.300 y =.600

As you can see, the stock filtering is plus-red (the x axis), yielding slightly yellowish greens.

Maybe when Cliff makes his swap I can measure the light loss through each element when they are uninstalled.


Ken Whitcomb

So big dog, are you recommending that I infact stick with my current c element????

Cliffy

Small world. Cliff you have a PM.

Art

So big dog, are you recommending that I in fact stick with my current c element????No, the Marquee C-element gets you close to the ideal x-axis coordinate for SMPTE green.

The stock element is probably still more light-transmissive, but this is a pretty inexpensive upgrade guaranteed to improve colorimetry.


Ken Whitcomb

No, the Marquee C-element gets you close to the ideal x-axis coordinate for SMPTE green.

The stock element is probably still more light-transmissive, but this is a pretty inexpensive upgrade guaranteed to improve colorimetry.


Ken Whitcomb

So now the proof is in the pudding.....

Thanks Big Dog.

Cliffy

Thanks for the data Ken. I am definitely going to change my green C-element now.

Can someone tell me the part number on the Marquee C-element please?

craigr

I was at Clarence's the other weekend, and had been wanting to measure a G90 with the Marquee C-element mod. I thought others might be interested in the comparison.

G90 (stock)
x =.330 y =.587

G90 w/Marquee C-element
x =.311 y =.603

SMPTE "C" green primary
x =.310 y =.595

SMPTE HD green primary
x =.300 y =.600

As you can see, the stock filtering is plus-red (the x axis), yielding slightly yellowish greens.

Maybe when Cliff makes his swap I can measure the light loss through each element when they are uninstalled.


Ken Whitcomb

Ken,

cool to hear that you took the measurements ! Some before and after measurements with regard to light loss would be much appreciated if you get the chance for it.

From my experiments with color filtering of HD8 equipped projectors I would guess the light loss would be somewhere between 15 to 20% when exchanging the stock C-element for the Marquee version, but I would be happy to hear it is less.

BTW: With the added filtering the G90 has almost exactly the same green as my 10 PG.

Oliver

Glad to see that someone else agrees with something I have been recommending and doing to G90's for years. I have had a number of calibrators state that they wouldn't cjange the CElement. I measured this a long time ago and found the correction to be pretty easy. I surprised that you didn't catch this before now Ken when measuring primary colors on G90 setups you did.
Back when Greg Rogers did the original review I believe that he observed that the Greens had a yellow to them. This is easily explained by the stock G CElement and easily corrected once you put the proper one in.
Any loght loss (whic I also measured years ago) would be a very small amount that could be easily gorrected by a few clicks of bias and gain and woundn't be enough to be perceved by eye.

Terry

So I guess I misunderstood your findings Ken. I thought that your comment regarding the difference relative to SMPTE and HD meant that it was not as big an issue as some had said and that the comment from wm regarding the fact that it was not wrong was where you stood on it as well................. :o

Art

So I guess I misunderstood your findings Ken. I thought that your comment regarding the difference relative to SMPTE and HD meant that it was not as big an issue as some had said and that the comment from wm regarding the fact that it was not wrong was where you stood on it as well................. :o

Art

Don't forget about the offer I made you big dog whenever your ready..... :)

Cliffy

Cliffy,
I replied to your post on Curt's F/S section about a red tube if your still looking??

Terry

So I guess I misunderstood your findings Ken. I thought that your comment regarding the difference relative to SMPTE and HD meant that it was not as big an issue as some had said and that the comment from wm regarding the fact that it was not wrong was where you stood on it as well................. :o

Art

Art,

I know that Ken posted his measurements for the stock filtered G90 before.

What you have to consider is that you probably need to push the green 15 to 20% harder in order to still have a picture as bright as you do now, so there definitely is a tradeoff with regard to light output.

Oliver

Art,

I know that Ken posted his measurements for the stock filtered G90 before.

What you have to consider is that you probably need to push the green 15 to 20% harder in order to still have a picture as bright as you do now, so there definitely is a tradeoff with regard to light output.

Oliver

Correct Oliver. I think he would be looking at at least 1fl per projector more vs. what he has now, which I dont think would be a problem for his minty tubes.......

I am trying to decide myself which direction to take right now as far as the proper element is concerned as I'm not stacking and I definitely dont want to lose light output.

Cliff

Cliffy,
I replied to your post on Curt's F/S section about a red tube if your still looking??

Terry

Replied. :)

Cliff I should know this by now but what size is you screen?

very interesting indeed, i'll remember this when I get a G90 in 2019 :( :D

-Gary

I surprised that you didn't catch this before now Ken when measuring primary colors on G90 setups you did.Terry,

I've known about this for a long time. This is just the first chance I've had to measure a G90 with the corrected green.

Any light loss (which I also measured years ago) would be a very small amount that could be easily corrected by a few clicks of bias and gain and woundn't be enough to be perceved by eye.If you would, please share the actual measured light loss with us. Thanks.


Ken Whitcomb

Cliff I should know this by now but what size is you screen?

Right now it's 96X72. I'll probably go bigger though for the G90.......

Cliff

Right now it's 96X72. I'll probably go bigger though for the G90.......

Cliff,

You'll go with 96" X 54" and like it!


Ken Whitcomb

Cliff,

You'll go with 96" X 54" and like it!


Ken Whitcomb

:D :D :D :D

After my experience with Bomrat today.......

Well, maybe yes. :)

Cliffy

I didn't feel like doing any real work today so while I was goofing off I figured why not...

Here are the DeltaExy and % RMS values I calculated for chromacity error with respect to both SMTPE "C" and "HD." I calculated the percent error for the stock C-Element and the Marquee upgrade.

If someone feels like checking the math here is my spreadsheet (http://www.cir-engineering.com/bin/rms.xls). Hopefully I didn’t make any errors in the math or the doc below, but everything seems logical :o

http://www.cir-engineering.com/bin/rms.gif

craigr

yep, you are a crazy calibrator for sure :D

-Gary

I forgot to mention that I'll be swapping out my G90's C-Element when I get back to the USA at the end of September. I'll do my own before and after with respect to chromacity, but I'm only using a CP5000 so I think Ken's PR-650 numbers are probably a little more reliable ;) I will take before and after luminance readings aimed at the projector with a 100 IRE field. Anyone want any other measurements besides chromacity and luminance? I'll maybe find some good real world scenes in movies to photograph as well.

craigr

With respect to SMPTE "C" the error dropped from 4.7% to just 1%.Since almost all material is still being produced using SMPTE C monitors, this is currently the more important improvement.


Ken Whitcomb

Since almost all material is still being produced using SMPTE C monitors, this is the more important improvement.

Exactly. And since a CRT can only have one chromacity at a time, I'm happy to see it closer to SMTPE "C." But I am also very please to see the dramatic improvement towards the HD standard as well.

Very nice little upgrade it seems :)

craigr

Nice work Craig, very nice indeed.
Also I have found that Sony with it's setting of 255 on the G Gain is overdriving the G tube which causes premature wear. Anyone want to buy some less than 1000 hr G G90 tubes cheap?
If you lower the gain to about 225 - 230, and calibrate the R & B for D65 the wear is not nearly as fast as 255. I personally put over 2K hrs on a G tube set up this way and there was just a very slight hint of wear that was almost impossible to see with the lens off. At 255, the wear would have been significant.

Terry

Yeah Craig, you give great math! ;)


Ken Whitcomb

Thanks guys.

I also just updated the SS with Delta Exy data.

craigr

Anyone want to buy some less than 1000 hr G G90 tubes cheap?


I'm interested. You have PM.

I went back and calculated the DeltaExy values for all four cases as well. The results are contained in the original post above and the SS has been updated.

craigr

Does anyone have the part number for the Marquee C-element? I've poked around the VDC website for a while and so far nothing's jumped out at me.

Hello

I have a few here still in Marquee castings for anyone interested. E.mail me.

Ken & Craig:

I hope you don't mind, but I've used some of your information on these Sony G90 C-Element Change instructions: http://www.curtpalme.com/Sony_G90_C_Element_Change1.shtm

Ken: I used your colorimeter readings of stock vs. Marquee c-elements.
Craig: I linked to your in-depth analysis paper.

I named you both by name and linked to your websites, so hopefully it'll drive some extra business your way. :)

Kal

Ken & Craig:

I hope you don't mind, but I've used some of your information on these Sony G90 C-Element Change instructions: http://www.curtpalme.com/Sony_G90_C_Element_Change1.shtm

Ken: I used your colorimeter readings of stock vs. Marquee c-elements.
Craig: I linked to your in-depth analysis paper.

I named you both by name and linked to your websites, so hopefully it'll drive some extra business your way. :)

Kal

Kal,

Your awesome dude! :D ;)

Cliffy